Digging up history

A new book unearths the cultural significance of soil.

ALL ABOUT DIRT: David Montgomery and his book, "Dirt: The Erosion of Civilizations."

Saving the world’s food supply is a dirty job — literally. In his new book, Dirt: The Erosion of Civilizations, David R. Montgomery argues that the rise and fall of great societies is profoundly connected to the ground people till.

Most of the book is spent chronicling the history of soil degradation — an epic tale of resource depletion through the depths of recorded time, from the Halls of Montezuma (collapse of some Mesoamerican societies, Montgomery notes, was exacerbated by slash-and-burn agriculture) to the shores of Tripoli (crops from North Africa’s farmlands fueled both Greek and Roman empires for centuries before erosion dried out its soils). Indeed, this subject is such fertile ground that readers may lose patience with Montgomery’s gopherlike habit of burying some of his best material far from the light of a topic sentence.

But despite these flaws, the book remains a compelling read. The sad lesson Dirt tells and retells is that we humans seem almost genetically predestined to misuse and neglect the resources beneath our feet, often rediscovering the significance of healthy soil only after it’s too late. As Montgomery points out, more than a few disasters in American history can be traced, at least in part, to erosion. During the ’30s Dustbowl, for example, careless agricultural practices caused some parts of the Great Plains to lose more than three quarters of their original top soil.

The closing three chapters focus on the absurdities of modern agriculture, chief among them that vast amounts of precious petrochemicals are now wasted replacing soil nutrients lost to lazy, erosive industrial farming techniques. Montgomery makes a persuasive case for “no-till” farming — surgically inserting seeds into the ground rather than churning up farmland that ends up getting washed or blown away. Because erosion is drastically reduced, farmers needn’t rely so heavily on fossil-fuel derived fertilizers to replenish the lost nutrients. Plus, the increased organic matter in the ground absorbs carbon dioxide, reducing greenhouse gases in the atmosphere.

Both the history and the polemics of Dirt are enlightening, well founded, and thoroughly researched. They are also sometimes littered with statistical and factual tillage.

The author’s encyclopedic grasp of geology, biology, and world history shines in the book’s stronger moments: He deftly argues, for example, that the Roman Empire’s self-destructive agricultural practices left a population vacuum that northern Italy’s fertile fields filled — a phenomenon that may have sowed the very seeds of the Renaissance. But within a paragraph this fascinating theory is cast aside, and Montgomery has moved into the more mundane territory of European cultivation statistics.

At times like this, one wishes Montgomery had seeded his own arguments a little less haphazardly and recognized that the historical narrative speaks for itself. As he demonstrates many times over, turn up too much dirt and it’s likely to be lost to the winds.

Story by Mark K. Anderson. This article originally appeared in Plenty in April 2007. The story was added to MNN.com in June 2009.